The invention relates to a full jacket-worm centrifuge, in particular for continuous separation of water-sludge mixtures. An approximately cylindrical drum jacket which is conically tapered in the direction of the solid matter discharge is provided together with a cylindrical conical worm conveyor arranged axially therein. A slurry feed is also provided as well as a drive for the cylinder jacket and worm conveyor.
In the case of full jacket-worm centrifuges of the cited type, the drum or cylinder jacket and the worm conveyor execute a rotational movement in the same direction but at a different speed. The slurry being fed is introduced through the slurry inlet into an annular chamber bounded between the interior side of the cylinder jacket and the worm conveyor, and is separated therein under the influence of an artificial field of gravity so that a solid matter layer is deposited from the liquid and is formed on the interior surface of the drum jacket. The liquid is conveyed through the exterior through a liquid drain opening, whereas the solid matter layer is transported by the worm conveyor, rotating at a different speed in relation to the drum jacket, to the conically tapered solid matter discharge of the drum jacket, and is finally discharged toward the exterior at the end of the conical drum member.
In the water-extraction (dehydration) of sludges, difficulties occur, in particular when the fineness of the solid materials and/or their density difference relative to the water are very small.
The discharge of the sludge-solid matter components concentrated in the centrifuge over the ascending region of the conical drum jacket presents particular difficulties. Under the influence of high centrifugal forces, a considerable tendency occurs for the solid materials to flow back in the direction of the cylindrical drum section.
Therefore, as can be learned e.g. from the German Offenlegungsschriften Nos. 1,532,678 as well as 2,612,696 both incorporated herein by reference, a radial disk or baffle has been arranged in the region of the transition from the cylindrical to the conical section of the cylinder jacket in order to thereby assist the transport into the conical jacket section.
Since this technique, itself, is not sufficient in most cases to guarantee a reliable discharge of the fine solid matter, it has also already been attempted to assist the transport of solid matter in the conical jacket section of the centrifuge through raising of the liquid level. However, this technique entails the disadvantage that the liquid component, which is discharged with the solid matter is relatively great and hence the water-extraction effect is relatively poor. The known measures and apparatus all have the disadvantage that, given fluctuating operating conditions, either the concentration or thickening effect or the clarification or purification effect is negatively influenced.